Abstract: An electronic high frequency supply, such as lamp ballast, includes a double rectifier, two storage Capacitors in series, and an isolating inductor between rectifier and an AC input. Each storage capacitor is charged to a voltage greater than peak of the AC input. An inverter is connected to the storage capacitors, and has a high frequency inductive load circuit connected between inverter output and a junction between the isolating inductor and double rectifier. A capacitor, connected from the junction to the junction of two storage capacitors, forms a high frequency resonance circuit with the inductive load circuit. Current is drawn from the input AC only as a series of pulses at the inverter frequency. The isolating inductor filters out the high frequency part of the current pulse and makes the input current near sine wave.

Abstract: A (vibration) stopper protection circuit of an electronic ballast for fluorescent lamps. The electronic ballast has an inverter to convert a direct current source into a square-wave source, and to provide the square-wave source to multiple lamp tubes. The stopper protection circuit has several harmonic oscillating capacitors, a sampling transformer, a protection signal processing circuit and a stopper circuit. The sampling transformer samples a normal sampling signal and an error sampling signal when the lamp tubes are normal or out of order, respectively. The protection signal processing circuit outputs an error signal while receiving the error signal. While receiving the error signal, the stopper circuit outputs a stop signal to the inverter, so that the inverter stops operating.